1. Field of the Invention
The present invention concerns an improved handling device mounted on a vehicle to carry out the handling of containers, skips, and any other load liable to be carried by the vehicle, as well as the procedure for its use.
2. Description of the Prior Art
There are already known handling devices mounted on vehicles which comprise a derrick of which the main telescopic arm is pivoted to the free end of a sub-frame which is itself joined by a transverse pivot to the rear end of the vehicle chassis. The mechanism is controlled by a slide jack allowing the main arm of the derrick to be extended and contracted, and by a tilting jack which is pivoted between the main arm of the derrick and the front of the vehicle chassis to tip the derrick and the sub-frame backwards and forwards. When it is desired to unload a skip or any other load on the vehicle, the tilting jack is extended and the derrick first swings about the pivot on the sub-frame, and secondly about the pivot on the chassis. When it is desired to "tip", that is to say empty the skip by inclining it downwards and backwards without unloading it, the main arm of the derrick is latched to the sub-frame in such a way that the extension of the tipping jack makes the whole assembly comprising the skip, the derrick and the sub-frame swing around the pivot at the rear of the chassis. The latching device which secures the main arm of the derrick to the sub-frame is preferably operated automatically by a first movement of the slide jack.
A handling device of this type is, for example, described in U.S. Pat. No. 3,988,035, owned by the assignee of the present invention and incorporated by reference herein.
One of the disadvantages of such a handling device is that it necessitates the use of a very powerful, and hence very expensive, tilting jack. In fact, the load to handle is very heavy, as much as 20 tons, and at the beginning of tilting the jack must provide a great initial starting force, given that its lever arm is very short on account of the fact that the tilting jack is almost horizontal, the lever arm being the distance which separates the line of action of the said jack from the axis of swing of the load. In fact, even with an oversize tilting jack, such a device does not allow the utilisation of skips and containers of standard dimensions of more than 20 tons in weight.